Xylan 1010, 1070, 1014, 1052 and now 1424 have been used as bolt coatings for almost a quarter century now. Most major Oil and Chemical Companies recognizing that maintenance is a huge issue have made coated bolt specifications for bolted high pressure flange connections. The various properties on the Xylan give excellent make up and brake out torque and reduce the need for high risk cutting torches or high cost bolt cutting when maintenance is required.

Xylan 1014 in bolt coatings used for its good lubricity, chemical and abrasion resistance.

Xylan 1052 for coated bolts used for its excellent lubricity.

Xylan 1070 and 1010 where the pioneers in the field – used for the lubricity and chemical inertness.

With VOCs an ever present issue these days Whitford has made a low VOC version 1424 which Sigma applies to achieve the results need in a coated bolt connection and to stay complaint in a green economy.

Xylan coated bolts come in many tints and the coated bolts are often coordinated with standard corporate color branding schemes. While very light shades are possible most of the popular hues range from a Dark Yellow to black with Reds and Blues and greens being the most widespread.

Tap end stud bolts are used in high pressure situations in the petrochemical industry for OEM and repair situations on flanged to main body connections. The tap end stud bolt has 2 A and 3A fit requirements to achieve complete connection

with one heavy hexagon nut, on the longer 2A fit side. The shorter 3A fit side is inserted into a threaded hole.

Stud Bolts

Inconel 718 is typically used in high strength applications where fastener operating temperatures can reach 700 degrees Celsius. Oxidization, thermal cycling and high pressures can create mayhem in bolted joints causing fasteners to loosen and lose grip strength. The top wellhead and valve OEMs count on High Temperature Bolting both Studs and Bolts for extreme temperatures applications. Sigma Fasteners is a leader in manufacturing Inconel 718 bolting.

The advantages of our Inconel 718 products include

Minimize oxidation and corrosion at high temperature.

Optional coatings to minimize galling.

Available in metric and Inch threads

Sigma can lower your cost for tap end studs with contract pricing or managed inventory.Sigma can supply nuts and bolts or studs.

Tap end studs have a short thread length on the tap-end side typically threaded tor Class UN-3A fit. This side is screwed into a tapped hole. The nut end of the stud is threaded with a Class UN-2A fit. Length of the stud is measured form end to end. The tap end has a chamfered point, but the nut end may have either a 30° or 45° chamfered end or round raduised end, at the customers option.The tap end can be measured from the end to last scratch, end of the chamfer to the last full thread or any combination of last scratch, last full thread, end or end of chamfer.

Tap-end studs in standard and exotic metals with multiple finishes:

ASTM B7, B7M, B8, B8M, 660,718, 17-4ph, MP35 and more.

Unfinished, SermaGard, Xylan, PTFE. Moly, zinc or cad plated.

Sigma can lower your cost for tap end studs with contract pricing or managed inventory.

REFERENCE
Stud bolts for high pressure & high temperature applications conform to the requirements of ANSI/ASME B16.5, Steel Pipe Flanges and Flanged Fittings.

LENGTH-FIRST TO FIRST
The length of stud bolt, measured parallel to the axis, is the distance from first thread to first thread. First thread is defined as the intersection of the major diameter of the thread with the base of the point. Please see the drawing above-this is confusing to most users!! Stud bolts are normally available from stock in 1/4 inch length increments. Length tolerances, all stud bolt sizes, shall be as tabulated below:

Length, in. Length Tolerance, in.
to 12 +/-0.062

over 12 to 18 +/-0.125

over 18 +/-0.250

POINTS
Points shall be flat and chamfered, or sheared at option of the manufacturer. When points are flat and chamfered, the diameter of the flat shall not exceed the minor diameter of the thread, and shall be not less than one or more than two complete threads as measured from the extreme end parallel to the axis.

MATERIAL
Chemical and mechanical requirements shall be specified by the purchaser and shall be in accordance with applicable ASME, ASTM, and ANSI codes and specifications current at the time of ordering.

ASTM Material Selection Chart – Stud bolas are available in ASTM A193 Grade B7, B7M, L7, L7M. As well as 660, 718 Inconel, Mp35N and other high nickel alloys and stainless steels.

DESIGNATION
It is recommended that stud bolts be designated in the following sequence: product name, nominal size, threads per inch, length, material, and protective finish, if required.

API 6A is an International Standard which specifies requirements and gives recommendations for the performance, dimensional and functional interchangeability, design, materials, testing, inspection, welding, marking, handling, storing, shipment, purchasing, repair and re-manufacture of wellhead and well tree equipment for use in the petroleum and natural gas industries.

*This chart is for general practice purposes only and should not be in the engineering or design of any products. The most current edition of the API specification may be obtained on the API Standards website to make sure you have the most current edition of API 6A. For most the accurate references in critical situations torque values should be replaced with field measured tension values. Accurate stud tension is difficult to attain using torque, because friction has a significant effect on the torque–tension relationship. Any thread damage (however minor), additional lubrication, or standard deviations within the range can change friction and thereby the expected outcome.